1. Field of the Invention
The present invention generally relates to a valve and, more particularly, to an improved valve assembly for a pipe flushing device.
2. Prior Art
U.S. Pat. No. 4,475,255 which issued to the inventor of the present application discloses an improved form of flushing device for unclogging water pipes and the like. Such device includes an elongated, generally cylindrical, elastomeric, hollow tubular member bearing a hose connector at its inlet end and a valve at its outlet end. The valve is in the form of a hard plastic or metal cage having a rigid transverse rear closure plate bearing a peripheral flange disposed in a transverse groove in the interior wall of the outlet. The groove is of a length greater than the thickness of the plate, but the plate diameter is such that the outlet wall grips the periphery of the plate to hold the cage in a fixed position and seal the outlet when the tubular member is in the unexpanded state. The cage has open sides and front.
When water is passed into the hollow tubular member through a hose connected to the inlet end thereof, while the tubular member is installed in a water pipe to be flushed, a cycle begins. First, the middle portion of the tubular member expands to the pipe diameter and causes the cage to slip rearwardly in the groove. This, in turn, causes a sonic vibration in the tubular member and pipe. The expansion also permits the expansion water to by-pass the plate in the groove as the plate is moved to a selected point rearwardly in the groove, the water passing out the outlet through the cage sides and front as a jet. This, in turn, results in a contraction of the middle portion of the tubular member, forcing the cage forward, causing a second sonic vibration and closing of the valve. The cycle then automatically repeats very rapidly so that water jet pulses and mechanical vibrations emanate rapidly from the device to easily dislodge the most stubborn pipe clogs. The jet expulsion also sets up strong mechanical vibrations in the device and pipe. The cycles are discontinued when water pressure is dissipated by disconnecting the hose from the device or bleeding water through the hose.
Such a device has proven to be very useful. However, it has also been found that inadvertent leakage of water around the rear closure plate frequently occurs, with some loss of efficiency.
It is believed that the leakage is due to the inability of the rear closure plate to conform to slight irregularities in the transverse groove in the tubular member outlet portion and also due to the fact that the plate is both hard and smooth and thus apt to slip out of place.
There remains a need for an improved valve which can provide a more positive water seal in the hollow tubular member, without sacrificing any of the desired functions of the flushing device. Such valve should be inexpensive, durable and conformable to a variety of transverse groove configurations.